US3502794A - Color television system utilizing phase-difference modulation - Google Patents

Color television system utilizing phase-difference modulation Download PDF

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US3502794A
US3502794A US563212A US3502794DA US3502794A US 3502794 A US3502794 A US 3502794A US 563212 A US563212 A US 563212A US 3502794D A US3502794D A US 3502794DA US 3502794 A US3502794 A US 3502794A
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phase
signal
subcarrier
chrominance
line
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Vladimir Efimovich Tesler
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N11/00—Colour television systems
    • H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
    • H04N11/12—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only
    • H04N11/14—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system

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  • FIG. 4 b COLOR TELEVISION SYSTEM UTILIZING PHASE-DIFFERENCE MODULATION Filed July 6, 1966 7 Sheets-Sheet 5 FIG. 4 a FIG. 4 b
  • FIG. 4 i FIG. 4 j
  • a characteristic feature of the proposed system lies in that the phase-difference modulation of the sub-carrier is used for transmitting information on color hue.
  • phase-difference modulation of the subcarrier makes it possible to avoid color distortions in the picture when there appear phase distortions in the communication channel and to preserve, at the same time, the positive properties of the balanced modulation, i.e., adequate compatibility and high noise resistance of the chrominance signal.
  • the present invention relates to color television systems employing a modulation of the chrominance subcarrier which shares the luminance frequency band.
  • a special synchronization signal is incorporated into the composite signal which is a chrominance sync burst comprising 10 to 12 oscillations of the reference subcarrier in the zero phase transmitted during the horizontal blanking pulse.
  • the sync burst is used to synchronize the subcarrier piezoelectric oscillator (the heterodyne), whose oscillations together with the chrominance signal (the subcarrier modulated in quadrature) is fed to phase detectors in which the modulating signals are separated.
  • the signals fed to the phase detector are substantially different not only in their composition, but also in those stray phase distortions which they have undergone while the color television composite signal has been passing through the communications channel.
  • the chrominance subcarrier signal in a general case, has a wide frequency spectrum of the order of three megacycles per second (both modulation frequency bands) and a nonuniformity of the phase characteristic of the channel in this signal frequency band, e.g., when suppressing one sideband, results in a stray phase modulation of the subcarrier.
  • the signal from the chrominance heterodyne which is synchronized by the sync burst which has passed through the narrow-band separation channel in the receiving device (inertia synchronization) is practically completely free of any stray phase modulation.
  • the chrominance subcarrier signal which occupies dif ferent levels of the luminance signal is subject to so-called differential-phase distortions when stray phase shifts of the subcarrier depend on the composite signal level (the communication channel being a quadripole with a nonlinear reactive impedance which depends on the level of the input signal). Therefore the sync burst is always on a constant level of the black in the signal and, hence, its differential-phase shift is, in a general case, different from that of the chrominance subcarrier signal.
  • one of the systems with the quadrature modulation does not meet the two basic requirements, viz., the insensitivity of subcarrier signals to stray phase modulation in the channel and maximum utilization of the channel for transmitting only useful information (since the second modulation sideband carries no information as compared with the first one and the second modulation sideband cannot be suppressed due to a stray phase modulation of the subcarrier).
  • the receiver of the system being described is complicated in servicing because of the necessity in two additional operation adjustments, namely, color hue (chromaticity) and saturation.
  • the method of shaping a composite chrominance signal by means of the quadrature modulation of the subcarrier and the sync burst transmission is the same as in that described above and therefore all the respective chrominance circuits in the receiver are preserved (the quartz-stabilized heterodyne of the subcarrier in particular).
  • a method of statistical error correction is used (a method of statistical accumulation).
  • An additional phase modulation of the chrominance subcarrier signal from line to line is introduced for this purpose at the transmitting end and, correspondingly, additional devices are incorporated in the receiver, namely a statistical accumulator of the chrominance signal made as a delay line for one line time with stages for algebraic summa tion of delayed and nondelayed signals, and also an elec tronic commutator to remove an additional phase modulation of the signal from line to line (a polarity reversal of one of the modulating signals).
  • the two necessary chrominance signals are transmitted alternately in an interlaced manner with the use of the frequency modulation of the subcarrier.
  • a delay line with a line period (a circuit store a previously transmitted signal) and two frequency discriminators are employed. Due to the employment of the memory device, both necessary chrominance signals are present in the receiver simultaneously, one as a delayed signal at the output of the delay line and another as a nondelayed signal at the input thereof.
  • the chrominance information is transmitted, as compared with the first system, and each of the two signals, due to the memory device, acts during the time of two lines.
  • Such a system however, also has several disadvantages, these being a smaller noise stability of the frequencymodulated subcarrier than it is the case with the quadra ture-modulated signal, this feature being especially pronounced at small signal levels (at signal-to-noise ratios close to the threshold values); the signal in the presence of noises becomes more sensitive to distortions of the amplitude-frequency characteristic. (If the ratio of the signal of the subcarrier attenuated by the amplitude-frequency characteristic of the channel to noise happens to be equal to or even less than the threshold value of 6 db, no correction at the receiving end is principally possible); and also a sensitivity to the suppression of one modula tion sideband.
  • said object is achieved due to the fact that the information on the chrominance signal is shaped in the encoding device of the transmitter and then transmitted by means of the phase-difference balanced quadrature modulation of the chrominance subcarrier in successive lines, with the laws of amplitude modulation in both lines being analogous and the phase modulations being different, and the phase of the subcarrier in one line being the reference one for shaping the chrominance subcarrier signal in the other line, the separation of the chrominance information in the receiver being effected by means of storage of the chrominance subcarrier signal which has arrived in the preceding line with the help of a delay line and detect ing a phase difference between the delayed and non delayed voltages of the subcarrier.
  • the shaping of the chrominance subcarrier signal can be effected by one of the two main methods.
  • a phase-difference interlace modulation is effected when the phase values of the subcarrier in adjacent lines which are transmitted in succession are different, their difference corresponding to the variation in the color hue (or chrominance) along the scanning line, while the method of the interlacing amplitude modulation of the subcarrier is the same.
  • the phase-difference interlacing modulation of the subcarrier can be effected in various ways. One of such Ways is a time interlacing phase-difference modulation of the subcarrier with the phase of the subcarrier in one line being constant.
  • the word line is generally to be understood as an abbreviation of the expression scanning line, but here means signal in time scanning line
  • the phase modulation in the second line is absent, the phase of the subcarrier signal oscillations equaling the reference phase.
  • a chrominance subcarrier for example, use is made during the time of one scanning line of the sum in the quadrature of the products of the subcarrier balanced modulation by two signals E and E
  • To shape a subcarrier signal during the time of the following scanning line use is made of theibalanced modulation of the subcarrier by the complex voltage equal to i.e., in the end, to shape the chrominance subcarrier signal during the time of this line use is made of the both colordifference signals.
  • the amplitude of the modulated subcarrier acting during the time of every scanning line carries information on the color saturation.
  • the interlacing phase-difference modulation can also be effected in a different manner when the phase modulation is preserved in both lines, for example, if the expression for the chrominance subcarrier signal in the first line is A-sin (w t-kg) then the expression for the signal in the second line (the chrominance subcarrier signal) should be where S2 is the frequency of the modulating signal and m -is an arbitrary value.
  • the phase of the subcarrier is equal either to 2m (1s0+) (a positive half-period of the modulating signal), or to (2m+1) (180+) l% and g 01' (p and 0 we can give the follonwing clarifications:
  • phase difference between B and E during the positive half period will be whereas during the negative half period it will be l o l -90) z+1s0
  • a line-wise phase-difference balanced quadrature modulation is employed, which is effected in such a manner that the phase of the subcarrier in each line of the image being transmitted is equal to the algebraic sum of the subcarrier phases in all the preceding lines of a given field.
  • the phases of the subcarrier in the lines can be summed either with an additional phase reversal from line to line or without it.
  • the value of the phase modulation (p (t) along one line (nl) is then used as a reference signal for shaping (i.e., for phase modulation) of the subcarrier p (t) in the following (nth) line.
  • arcton is the term signifying that in each even-numbered line there is transmitted a signal, which is a result of the balanced modulation of the subcarrier by means of a unipolar signai (i.e., that there is no phase reversal through 180 at a frequency 9 of the modulating signal).
  • the signal in case of the alternativerating line-wise phase-difference modulation of the subcarrier will not diifer from the signal obtained with the use of the time interlacing phase-difference modulation with a constant phase in one line.
  • the vertical color definition in the image on the receiver screen will be complete and the employment of the signal at the receiving end will not diifer from the case of transmitting signal with the interlacing phase-difference modulation of the chrominance sub-earrier (the structure of the chrominance circiuts in the receiver remaining the same).
  • the expressions for the chrominance subcarrier signal may be written as
  • the absence of the additional phase modulatiion of the subcarrier i.e., of the sign reveersal before (p effected from line to line makes it possible to simplify somewhat the use of signals in the receiver, since then there is no need in removing this additional phase modulation.
  • a subcarrier with a zero phase modulation is used for shaping the first line of each field.
  • FIGS. 1a, b, c, d shows vector diagrams of chrominance subcarrier signals in case of using time interlacing phasdifference modulation of the subcarrier (with a constant phase in one of the lines);
  • FIGS. 2a, b, c, d shows vector diagrams of chrominance subcarrier signals in case of using time interlacing phasedifference modulation the subcarrier with a half phase modulation);
  • FIG. 34.1, c, d, e, f, g, h, i, 1 shows vector diagrams of chrominance subcarrier signals in case of using a linewise alternating phase-diflerence modulation
  • FIG. 4a, b, c, d, e, f, g, h, i, j shows vector diagrams of chrominance subcarrier signals without an additional reversal of the phase modulation sign from line to line;
  • FIG. 5 shows a simplified block diagram of the encoding device of the transmitter of the system for shaping composite color television signals with the use of time interlacing phase-difference modulation of the subcarrier (with a constant phase of the subcarrier in the first of the lines transmitted in succession);
  • FIG. 6 shows a simplified block diagram of the encoding device of the transmitter of the system for shaping composite color television signals with the use of time interlacing phase-difference modulation of the subcarrier (with a fhalf phase modulation);
  • FIG. 7 shows a simplified block diagram of the encoding device of the transmitter of the system for shaping composite color television signals with the use of a linewise alternating phase-difference modulation of the sub carrier;
  • FIG. 8a, b shows vector diagrams of decoding chromi nance subcarrier signals in case of time interlacing phase difference modulation with a constant phase in one of the lines transmitted in succession;
  • FIG. 9a, b shows vector diagrams of decoding chrominance subcarrier signals in case or" a line-Wise phase-difference modulation without an additional reversal of the phase modulation sign from line to line;
  • FIG. 10 shows a simplified block diagram of a color television receiver
  • FIG. 11 shows a simplified block diagram of chrominance circuits in the receiver for decoding color television signals in case of using time interlacing phase-difference and a line-wise alternating phase-difference modulation of the subcarrier;
  • FIG. 12 shows a simplified block diagram of chrominance circuits in the receiver for decoding color television signals in case of using a line-wise phase-difierence modulation of the subcarrier Without an additional reversal of the phase modulation sign from line to line.
  • FIG. la, b, c, d are vector diagrams of chrominance subcarrier signals in the first and second lines during the negative and positive half-periods of the modulating signal with the use of time interlacing phase-difference modulation of the subcarrier with a constant phase in one line; shown in FIG. 2a, b, c, d are vector diagrams for the time interlacing phase-difference modulation with a half phase angle. While with the reversal of polarity of the modulating signal from positive to negative one (FIGS.
  • phase of the subcarrier in the first line changes through in accordance with the expression for the signai of the first line
  • the second line (FIGS. 1c, d, 20, d)
  • the phase difference of the subcarrier in the first and second lines during the positive half-period of the modulating signal will be equal to oortow 9 and during the negative half-period of the modulating signal, to
  • FIG. 3a, b, c, d, e, f, g, h, i, j are vector diagrams of chrominance subcarrier signals in case of a linewise alternating phase-differenc modulation also during positive and negative half-periods of the modulating signal in five lines transmitted in succession.
  • the expression for the chrominance subcarrier signal in each line E (FIG. 3a, b), E (FIG. 30, d), E (FIG. 3e, f), E (FIG. 3g, h) and E (FIG. 31', j) takes the form From the drawings and the expression given above it can be seen that the phases of the subcarrier signals E E and E in positive and negative half-periods are different by 180 while the phases of signals E and E remain unchanged.
  • b, c, d, e, f, g, h, i, j are corresponding vector diagrams of the chrominance subcarrier signals in five lines for a positive and a negative half-periods of the modulating signal.
  • FIG. 5 Shown in FIG. 5 is a simplified block diagram of the decoding device of the transmitter for shaping a composite color television signal with time interlacing phase-diiference modulation of the subcarrier (in case of using a constant phase in one of the two lines transmitted in succession).
  • Color signals E E and E coming from the transmitter of color images, e.g., from a studio transmitting camera, are fed to unit 1 of matrix converters, whereto the necessary impulse signals E; from the synchronizing generator are also fed.
  • matrix circuits of the unit 1 three video signals are shaped, luminance signal E and two color-difference signals E and E respectively.
  • luminance signal E From the output of unit 1 luminance signal E is fed to unit 2 in which the luminance signal is summed with the chrominance subcarrier signal, and also the amplification and necessary processing of the composite color television signal Ey-l-E are effected, which composite signal is then fed to the television radio transmitter. From the output of the unit 1 color-difference signals E and E come to unit 3 of balanced quadrature modulation, whereto the voltage of the reference subcarrier with angular frequency w is also fed.
  • the unit 3 there is shaped quadrature-modulated chrominance signal E A -sin (w t-Hp) by summing in quadrature two balance-modulated voltages K E -cos w t and K E -sin w t. From the output of the unit 3 the signal E is fed to the inputs of commutator 4 and of unit 5 in which the envelope of the quadrature-modulated voltage of E is separated, e.g., by means of amplitude detection.
  • the voltage from the output of the unit 5 equal to 1 itz izis fed to balanced modulator 6, whereto, as well as in case of the unit 3 of balanced quadrature modulation, there is also fed the reference subcarrier voltage sin w t.
  • the output signal from the balanced modulator 6, equal E A sin w t is applied to the second input of the commutator 4, from whose output signals E or E are taken alternatfely in an interlacing manner.
  • These two successive signals from the output of the commutator 4 are fed to unit 7 of the amplitude pre-distorter, whose output voltage, proportional to /K is fed to the unit 2 to be summed with signal E i.e., for shaping a composite color television signal.
  • additional signals in the form of modulated or non-modulated subcarrier burst during several lines (these additional signals being shaped within the E and E signal complexes).
  • additional signals can be used in the receiver for some auxiliary purposes, such as for controlling the initial state (phase) of the commutator and the operation of the automatic chrominance adjustment system.
  • the subcarrier bursts in the E complex should have the phase of and in the E complex their phase should be equal to the reference one (that is, to zero).
  • FIG. 6 A simplified block diagram of the encoding device for shaping composite color television signals with the time interlacing phase-difierence modulation of the subcarrier in case of using a half phase modulation, is shown in FIG. 6.
  • signals E E E and impulse signals E from the synchronizing generator are fed to unit 1 of matrix converters and from the output of the unit 1 signals E are fed to unit 2 of summation and color-difference signals are fed to unit 3 of balanced quadrature modulation.
  • color-difference signals E and E are fed also to unit 8, in which these signals are converted into uni polar ones, so that voltages at the outputs of the unit 8 are proportional to E and E respectively.
  • modulus voltages are fed to an additional unit 9 of balanced quadrature modulation, whose circuit is quite similar to that of the unit 3.
  • auxiliary signals in the form of several lines of either modulated or nonmodulated subcarrier, which can be used in the receiving device both for phasing the commutator and for controlling the circuit of the automatic control and adjustment systems of the chrominance channel.
  • FIG. 7 A block diagram of the device for shaping a composite color television signal with a line-wise alternating phasedilference modulation of the subcarrier is shown in FIG. 7.
  • chrominance signals E E E; from the synchroniZing generator are fed to unit 1 of matrix converters, in which three video signals are shaped, viz., luminance signal E and two color-difference signals, say, E and E
  • the luminance signal E from the output of the unit 1 is fed to the unit 2 of summation where the shaping of the composite color television signal (by summing the signal E with the chrominance subcarrier signal E its amplification and the necessary processing prior to feeding to the television transmitter are effected.
  • the color-difference signal EB y from the output of the unit 1 is fed to balanced modulator 12, and the signal E through commutator 11 which changes its polarity from line to line, is fed to balanced modulator 13.
  • the output voltages of the chrominance subcarrier from balanced modulators 12 and 13 equal in their amplitude to K E and iK1E respectively, are fed to unit 14 of summation, at whose output there appears the voltage of the chrominance subcarrier signal E proportional to the quadrature sum of voltages from the balanced modulators 12 and 13.
  • the amplitude of the signal E is equal to the voltage of the modulated subcarrier form the output of the unit 14 of summation is fed in parallel to two units, namely to unit 7 of the amplitude pre-distorter (pre-emphasis filter) in accordance with the square root law and to phase-separation unit 15.
  • unit 7 of the amplitude pre-distorter pre-emphasis filter
  • phase-separation unit 15 From the output of the unit 7 of the amplitude pre-distorter the modulated chrominance subcarrier signal is fed to the unit 2 of shaping a composite color television signal equal to
  • suppression of the amplitude modulation of the chrominance subcarrier signal is effected.
  • the voltage of the reference subcarrier sin w t is fed.
  • a self-exciting oscillator with a weak feedback which is pulled-in by the oscillations of the input signal (chrominance subcarrier).
  • a subcarrier voltage with a constant amplitude but modulated in phase in the same way as the input chrominance subcarrier signal i.e., the voltage is in phase with the quadrature-modulated signal at the input. If the amplitude of the input quadrature modulated voltage is equal to zero, the phase of the subcarrier voltage at the output of the unit 7 is also equal to zero (i.e., to the phase of the reference subcarrier sin w t.
  • This voltage, delayed for one line time by means of an ultrasonic delay line 16 is fed to a wideband phase splitter 17 from whose outputs two voltages of the subcarrier modulated in phase according to the same law shifted by with respect to each other, are fed to the balanced modulators 12 and 13 as a reference voltage for shaping the quadrature-modulated voltage of the chrominance subcarrier (chrominance signal) in the subsequent line.
  • the elements and the mode of operation of the blockdiagram of a device for shaping a composite color television signal with the line-wise phase-difference modulation of the subcarrier without an additional reversal of the phase modulation sign from line to line do not diifer from the respective elements and their mode of operation in the block diagram of the device shown in FIG. 7.
  • the only difference between these block diagrams is the absence of the commutator 11 which in the block diagram of FIG. 7 serves for effecting the alternating phase modulation of the subcarrier.
  • the principle of using said signals in the receiving device is their matching in time by means of a memory device, e.g., a delay line for one line time.
  • chrominance subcarrier signal transmitted during the preceding line time interval (delayed signal) Witha shift and without it; as a decoded signal there is used a nondelayed chrominance subcarrier signal. If, instead of a delayed signal, a nondelayed signal is used for the axes of decoding, the results will be only in the reversal of the sign of the color-difierence signal E being separated.
  • FIGS. 8a, b are diagrams of decoding only for one of these versions, namely, for the time interlacing phasedifiference modulation with a constant phase.
  • the diagram, shown in FIG. 8a pertains to the time demodulation of the n-th line
  • FIGS. 9a, b are diagrams for the case of the line-wise phase-difference modulation of the subcarrier without the additional reversal of the phase modulation sign from line to line.
  • the diagram of FIG. 9a pertains to the time, of decoding the itth line when the signal is delayed
  • the diagram presented in FIG. 9b pertains to the time of decoding the (n+1)th line when the signal I is delayed.
  • the signal from antenna 18 comes to stages 19 of high frequency amplification and of the converter in the unit adapted for switching over television programs. Then the signal at the intermediate frequency is amplified in an intermediate frequency amplifier 20, and at the load of the first detector 21 there is separated a composite color television signal E -l-E which is fed to amplifier 22 of luminance signal E and through bandpass filter 23 to chrominance unit 24. From the hutputs of the chrominance unit 24 chrominance video signals are taken off, e.g., Egg, E and E These signals, together with the luminance signal E are fed, e.g to a three-gun kinescope or anyi'other reproducing device, controlling the luminance and chrominance of the image on the receiving screen. W i
  • the signal, necessary forjthe synchronization of generators 26 and 27 of horizontal and vertical scanning respectively are obtained from selector 25 of synchronizing pulses.
  • FIG. 11 is given a'simplified block; diagram of circuits for decoding chrominance subcarrier signals in cases when the composite color television signal is trans- 'mitted with the use of the time interlacing, as well as of the line-wise alternating phase-difference modulation of the subcarrier.
  • the voltage of the chrominance subcarrier from the bandpass filter 23 is fed to the inputs of delay line 28, phase detector 29 and wide band phase inverter 30.
  • the chrominance subcarrier signal having been turned in the phase inverter 30 through 90 is fed to commutator 31 in which its phase is turned through 130 at a line frequency.
  • the signal at the output of the commutator differs from the input signal by 180 with respect to the phase, and during the period of the second line the input and the output signals of the commutator are in phase.
  • the voltage from the output of the eommutator 31 is fed to the second phase detector 32. Besides these (nondelayed) signals, to.
  • the phase deteetors 29 and 32 there is also fed the voltage of the chrominance subcarrier from the output of the delay line 28 (the,delayed signal from the preceding line). Due to the multiplication of the delayed :and the nondelayed voltages of the chrominance subcarrier in the phase detector s 29 and 32, at the outputs of ;said detectors thpre appear color-difference video signals E and E respectively.
  • the third color-difference signal E is obtained in matrix circuit 33 by summing E and E taken in certain proportions and with certain polaritiesr
  • the operation of the commutator 31 is controlled by line frequency pulses from theihorizontal scanning generator 26 of the receiver.
  • stage 34 pan be employed, whereto there comes a pulse arising in the signal E during the frame blanking interval, when in the chrominance signal complex there is transmitted an identification signal in the form of bursts of modulated or non-modulated subcarrier.
  • the same signal can be used for controlling the chrominance control and adjustment system.
  • a simplified block diagram oflthe chrominance circuits of the receiver, used for receiving color televi: sion signals with a line-wise phase-dilferenceemodulation of the subcarrier without additional reversal of the phase modulation sign from line to line is shown in FIG. 12. The difference between this block diagram and that shown in FIG.
  • a color television system in which a subcarrier is employ ed which shares the frequency band of the luminous signal, said system comprising means for shaping chrominance information including a transmittenencoding device; means for transmitting said chrominance information by phase-difference balanced quadrature modulation of the chrominance subcarrier in successive lines in such a way that the amplitude modulations in said successive lines are analogous and the phase modulations are diiferent'to produce a chrominance, the phase of the chrominance signals in one of said lines being the reference for shaping the chrominance signal in the other of said lines; means for separating the chrominance information thus transmitted in the receiver by storing the chrominance signal which has arrived in the preceding line, the latter said means'includirrg a delay line; and means for detecting the difference between the phases of the delayed and non-delayed chrominance signals.
  • a color television system in which a subcarrier is employed which shares the frequency band of the luminance signal, said systemwomprising means for shaping chrominance information'including a transmitter encoding device; means for the phase-difference modulation of the chrominance subcarrier in successive lines to transmit said chrominance information, as a chrominance signal said phase-difference modulation being elfected in a time interlacing manner in such a way that the phase of the chrominance signal in one of thetsuccessive lines is constant while the phase in another of said successive lines varies in accordance with the variation of the chrominance of the scene'being transmitted; means for separating said chrominance information-in the receiver by storing the chrominance signal which has arrived in the preceding line, the iatter said means including a delay line; and means for detecting the difierence between the phases of the delayed and non-delayed chrominance signals.
  • a color television method in which a subcarrier is employed which shares the frequenc'y band of the lumifiance signal, said' method comprising shaping chrominance information in the encoding device of the transmitter; transmitting said shaped chrominance information by phase-difference modulating the subcarrier in a time interlacing manner in such a way that the phase angles of said subcarrier in successive lines are equal in each moment of time to the half et the phase angle corresponding to the chrominance in a given point of the scene being transmitted, the signs of said phase angles in the successive lines being opposite; separating said chrominance information in the receiver by storing the chrominance signal which has arrived in the preceding line; and detecting the dilference of phases of the delayed and nondelayed chrominance signals, e
  • a color television method in which a subcarrier is employed which shares the frequency band of the luminance signal, said method comprising shaping encoded chrominance information; transmit 'ng said information by phase-difference modulation the subcarrier in a linewise manner with an alternating sign of the phase modulation from line to line to produce a chrominance signal such that the value of the phase angle of the chrominance signal in each point of the line is equal to the difference of the algebraic sums of the phase angles in points located on the same vertical line of [all odd-numbered and all even-numbered lines of a given field; separating in the receiver of said chrominance information by delaying and storing the chrominance signal which has arrived in the preceding line; and detecting the difference between the phases of the delayed and non-delayed chrominance signals.
  • a color television method in which a subcarrier is employed which shares the frequency band of the luminance signal, said method comprising shaping encoded chrominance information; phase-difierence modulating said subcarrier in a line-wise manner so that the instantaneous value of the phase of said subcarrier in each of the two successive lines being transmitted is equal to the algebraic sum of the phase angles of all the points lying on the same vertical line in the preceding lines of a given field plus the phase angle corresponding to the chrominance in a given point of the scene; separating said chrominance information by delaying and storing the chrominance signal which has arrived in the preceding line; and detecting the difference between the phases of the delayed and non delayed chrominance signals.
  • a color television system in which a subcarrier is employed which shares the frequency band of the luminance signal, said system comprising a transmitter; encoding means in said transmitter adapted to shape chrominance information; means for the phase-difference modulation of the chrominance subcarrier in successive lines in said transmitter to transmit said shaped chrominance information as a chrominance signal such that the amplitude modulations in successive lines are analogous and the phase modulations are different, the phase of the chrominance signals in one of said lines being the reference for shaping the chrominance signal in another of said lines; a receiver including means for separating said chrominance information and a delay line for storing the chrominance signal which has arrived in the preceding line; and a detector of the diiference between the phases of the delayed and non-delayed chrominance signals, said detector being coupled to said receiver.

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  • Processing Of Color Television Signals (AREA)
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CH1051165A CH452593A (de) 1965-07-27 1965-07-27 Farbfernsehverfahren und Einrichtung zur Durchführung des Verfahrens

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US (1) US3502794A (fr)
CH (1) CH452593A (fr)
CS (1) CS161199B1 (fr)
DK (1) DK119265B (fr)
FI (1) FI44258B (fr)
GB (1) GB1090848A (fr)
NO (1) NO118671B (fr)
SE (1) SE345945B (fr)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3213191A (en) * 1960-09-09 1965-10-19 Cft Comp Fse Television Methods and circuitries for transmitting a color television sub-carrier

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3213191A (en) * 1960-09-09 1965-10-19 Cft Comp Fse Television Methods and circuitries for transmitting a color television sub-carrier

Also Published As

Publication number Publication date
CH452593A (de) 1968-03-15
SE345945B (fr) 1972-06-12
GB1090848A (en) 1967-11-15
CS161199B1 (fr) 1975-06-10
NO118671B (fr) 1970-01-26
FI44258B (fr) 1971-06-30
DK119265B (da) 1970-12-07

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